Joined by Prime Minister Tony Abbott, Governor-General Sir Peter Cosgrove and New Zealand high commissioner Chris Seed, Prince William and Catherine looked on as a procession of returned and current servicemen and women passed by.

A large contingent of military cadets and scouts also marched, demonstrating the popularity of Anzac Day among younger generations.

The AWM says a record crowd of about 25,500 attended the daytime national service and march, 8,000 more than last year.

Speaking at the memorial, Mr Abbott paid tribute to service personnel from all World War I campaigns.

"Today we remember the Gallipoli landing, yet this was just one day, and Gallipoli was but one campaign in a four-year war," he said.

"On the 99th anniversary of Australia's baptism of fire, we remember that fateful day."

Mr Abbott said World War I "impacted Australia like nothing else before or since".

"We also remember the great tide of events of which Gallipoli was just one part that shaped our nation, and that still casts its shadow over the wider world," he said.

The Royal couple also laid flowers at the Tomb of the Unknown Soldier and added poppies to the Roll of Honour.

They then planted a pine tree propagated from the memorial's original Lone Pine, which was planted in 1934.

The original was sown from seed collected from the site of the Battle of Lone Pine in 1915 and is nearing the end of its life.

The new pine will serve as a replacement for the day the original dies and will continue as a living memorial to Australia's wartime past.

"It was good to see the Royal couple wanted to share our national day with us, that was fantastic," said Air Force veteran Ian Scott from Wentworth Falls, New South Wales.

"It was a nice, simple service. You always remember relatives that died in World War II and mates that are gone."

Dawn tribute to the fallen

Prince William and his wife also made a surprise appearance at the AWM's dawn service to hear tributes to those who fought and died in war.

In his commemorative address, Victoria Cross recipient Corporal Ben Roberts-Smith urged people to remember the thousands of wounded soldiers and the continuing challenges they face.

"The physical scars inflicted will remain their curse and inspiration for life," he said.

It's a fundamental human yearning to be a part of something bigger than one's self, and maybe that's what drove my mate Ash to die, far from home, in a bloody foreign war against Islamic State, writes C August Elliott.